1. Field of the Invention
The present invention relates to an ink jet recording head, an ink jet head unit and an ink jet apparatus, the ink jet recording head and the ink jet head unit being for use with the ink jet apparatus which performs the recording by discharging the liquid (e.g., ink) for recording as tiny liquid droplets through discharge ports to attach onto the recording medium, and more particularly to an ink jet head, an ink jet head unit and an ink jet recording apparatus for the color printing. The term "recording" for use with the present invention includes the printing onto cloth or plastics.
2. Related Background Art
A conventional ink jet recording head is comprised of a ceiling plate (grooved member) 1120 having a plurality of discharge ports 1105 for discharging the ink, a recess portion 1118 which is a common liquid chamber for holding the ink to be supplied to discharge ports 1105, and ink flow passages 1106 for communicating the common liquid chamber to discharge ports 1105, and a silicon substrate 1119 on which electrothermal converters (not shown) for supplying discharge energy to the ink within ink flow passages 1106 are formed corresponding to the ink flow passages 1106, the silicon substrate being joined with the ceiling plate, as shown in FIG. 37 (a perspective view as looked from the opposite side of the discharge ports) and FIG. 38 (a perspective view of the ceiling plate as looked from the side of its junction face with the substrate). Also, the silicon substrate 1119 has a drive circuit for driving the electrothermal converters incorporated therein, this drive circuit being electrically connected to wire bonding pads 1122 formed at the end portion of the silicon substrate 1119. And the silicon substrate 1119 is bonded by thermally conductive adhesive with an aluminum plate 1121 for releasing the heat from the silicon substrate 1119. The aluminum plate 1121 has a wiring substrate 1125 secured thereto, which relays the signal between the drive circuit and the ink jet recording apparatus, the terminals of the wiring substrate 1125 and the wire bonding pads 1122 of the silicon substrate 1119 being electrically connected through bonding wires (external wires) 1123.
On the other hand, in making the color printing, an ink jet unit 1150 having an arrangement of a plurality of ink jet recording heads 1151 for discharging the inks of different colors is used, as shown in FIG. 39. However, in this case, the size of the apparatus 1is difficult to reduce because of the employment of the plurality of ink jet recording heads 1151, and the cost of the apparatus will be increased by the amount corresponding to the number of ink jet recording heads 1151, although the apparatus has the advantage of the fast printing.
To resolve the above-mentioned problem, the inventors have attempted to create a small and inexpensive ink jet head in such a way as to use a pressing force of a spring to force a grooved member having recess portions corresponding to a plurality of liquid chambers into contact with an element substrate having a plurality of electrothermal converters.
However, in the case of such ink jet recording head, because a separation wall (liquid chamber wall) for separating between each liquid chamber is formed integrally with the grooved ceiling plate, it is apprehended that a gap may arise between the grooved ceiling plate and the substrate in a portion of this separation wall, as above described, so that owing to this gap, the ink within each liquid chamber may permeate or diffuse, in which there is a risk of producing the color mixture of inks, with the degraded quality of the recorded image.
It is conceived that a sealant is provided in the gap between this separation wall and the element substrate like the external periphery of a junction portion between the substrate and the grooved ceiling plate, but too much sealant may overflow into adjacent flow passages, or too little of sealant can not make the sealing of the separation wall portion completely, whereby the amount of sealant is difficult to control, and the separation between adjacent liquid chambers could not be securely made.